Optical Disk Recording Pulse Correction for Interference Reduction
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Solution Overview
Problem
Existing optical disk technologies face challenges in further increasing recording density due to insufficient reduction of optical intersymbol interference and thermal interference, particularly at higher densities beyond those supported by BDXL standards.
Innovation Solution
An optical disk recording method that encodes data using modulation codes, classifies run lengths of marks and spaces, and adjusts recording pulse positions based on evaluation indices from maximum likelihood decoding, employing extended L-SEAT operations to minimize interference and improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recording density is increased beyond BDXL standards, then recording capacity is improved, but optical intersymbol interference and thermal interference increase
Solution Approach 1:
The patent changes the parameters of the recording pulse by calculating correction amounts based on extended L-SEAT operations. The correction amount adjusts the start position and duration of recording pulses according to the specific pattern of surrounding marks and spaces, optimizing the recording conditions for each local context to minimize interference effects.
Solution Approach 2:
The patent performs preliminary calculation of correction amounts before actual recording by analyzing the encoded data pattern in advance. The extended L-SEAT operation evaluates multiple possible patterns and determines optimal correction values beforehand, allowing the recording process to proceed with pre-optimized parameters that compensate for anticipated interference.
2Quantity of substance
If mark length is reduced to increase density, then recording capacity is improved, but signal quality and error rate worsen
Solution Approach 1:
The patent applies different correction strategies to different local patterns of marks and spaces. By classifying patterns based on the lengths of surrounding marks and spaces (2T, 3T, 4T, 5T, 6T, 7T, or more), the system tailors the recording pulse correction amount to each specific local context, ensuring optimal signal quality for each pattern type even when marks are smaller than the optical spot size.
3Object-affected harmful factors
If conventional adaptive recording compensation is used, then some interference reduction is achieved, but interference reduction is insufficient for further density increases
Solution Approach 1:
The patent segments the interference compensation into multiple classification categories based on the specific patterns of surrounding marks and spaces. Instead of using a single correction value, the system divides the data into multiple classes (7T or more, 6T, 5T, 4T, 3T, 2T) and applies specific correction amounts to each class, providing more granular and effective interference reduction.
Solution Approach 2:
The patent introduces the extended L-SEAT operation as an intermediary calculation step between data encoding and actual recording. This intermediary process evaluates multiple patterns and calculates optimal correction amounts that mediate between the conflicting requirements of high density and low interference, enabling the system to achieve both goals simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces optical intersymbol interference and thermal interference, enabling higher recording densities with improved signal quality and reduced error rates, even for marks and spaces below the optical spot size.
Implementation Method 1
irradiating an optical disk with an optical beam to form a plurality of marks on a medium
Implementation Method 2
forming a mark according to the recording data on the medium of the optical disk by changing a power of the optical beam in a plurality of stages
Data Source
AI summary
A mark corresponding to recording data is formed on an optical disk by: encoding the recording data in accordance with a modulation code and generating encoded data; classifying the encoded data by a combination of at least two of a mark length of a mark, a space length of a preceding space, the mark length of a preceding mark, and the space length of a succeeding space; setting a correction amount for adjusting the position of the start edge and the end edge of a recording pulse based on an evaluation index of a decoding result, which is a result of decoding a reproduction signal of the encoded data, for each of the classification; and generating the recording pulse corresponding to the encoded data by using the correction amount corresponding to the classification of the run length of the encoded data.